In the mixing of large bodies of liquid, several different types of mixers have been used, such as water floats and pumps. Generally, the floatation type is not sufficiently controllable in all directions of flow for efficient mixing. Further, pumps and the like are susceptible to clogging and often do not provide sufficient rate of flow for the efficient mixing required in equalization basins, as well as oxidation ditches, sludge holding tanks and other special applications. Mixers are also used in aerated lagoons in which active biological solids are in equilibrium with an applied waste. The basin is of sufficient depth, normally six to twelve feet and oxygen is furnished by mechanical aeration to create a turbulence level sufficient to provide adequate liquid mixing. As a result of the mixing, uniform distribution of the waste and dispersion of the oxygen is achieved and rapid and efficient waste biodegration occurs.
Mixers such as the Flygt 4500 Submersible Mixer have been employed with generally acceptable results for mixing in tanks, ponds and lagoons. However, such mixers are often not sufficiently controllable in direction of flow for maximum efficiency. For example, the Flygt mixer does not have tilt capability wherein the motor and propeller can be positioned above the high concentration of bottom settled solids in a tank and flow thereof created from the bottom of the tank to loosen packed solids settled out along the tank bottom. Rather, the mixer must be positioned horizontally as close to the bottom of the tank as possible wherein level mixing occurs which indirectly tends to stir the tank bottom.